Stairclimbing wheelchair



May 19y 1954 E. M. RlcHlsoN ETAL 3,133,742

STAIRCLIMBING WHEELCHAIR Filed Oct. 8, 1962 5 Sheets-Sheet l May 19, 1964 E. M. RlcHlsoN ETAL 3,133,742

STAIRCLIMBING WHEELCHAIR Filed Oct. 8, 1962 5 Sheets-Sheet 2 lULllll:

4 Woven/g5. Ys.

May 19, 1964 E. M. RlcHlsoN ETAL i 3,133,742

STAIRCLIMBING WHEELCHAIR Filed Oct. 8, 1962 5 Sheets-Sheet 3 FVG. 5. 44

r\ .EN

INVENTORS.

EUGENE /14 ,/CA//So/V,

47' TOeA/E V152 United States Patent O 3,133,742 STAIRCLHVIBHJG WHEEIJCHAIR Eugene M. Richison and Ethel M. Richison, Kinta, Okla., assiguors of twenty-five percent to T. H. Conklin, Stigler, Okla.

Filed Oct. 8, 1962, Ser. No. 229,244 14 Claims. (Cl. wil-5.28)

This invention relates to a novel stair and curb-climbing wheelchair.

The primary object of the invention is the provision of a safe, mechanically eicient wheelchair of the kind indicated, which is easily operated by hand by an occupant thereof for climbing or descending stairs and curbs, and whose climbing mechanism is adapted to be manually retracted by the occupant, when not in use, so that it does not interfere with normal operation of the device on its wheels; and wherein depression of the climbing mechanism, to operative position is accompanied by tilting back of the seat and back of the wheelchair, so that the occupant is more safely seated during a descent or ascent of stairs and the like.

Another object of the invention is the provision of a wheelchair of the character indicated above, wherein the climbing mechanism comprises climbing assemblies mounted to the opposite sides of the wheelchair, each of which comprises pairs of longitudinally reciprocable traction shoes which are alternately depressed into stair or curb-engaging positions and moved longitudinally in contact therewith, in rearward or forward wheelchair moving directions, the traction shoes being operated by separate hand-crank means mounted on an upper part of the sides of the wheelchair, whereby the wheelchair can be steered and guided, up or down stairs or curbs, by controlled manual operation of the hand-cranks.

A further object of the invention is the provision of a wheelchair of the character indicated above, wherein the traction shoes compri-se anchored flexible and resilient bars on whose undersides are fixed compressible and resilient rubber or rubber-like traction teeth; and wherein each climbing assembly is provided with driven forward and rear climb-starting wheels, provided with similar material teeth, which are operated by the hand-cranks through the traction shoe driving means, and which render safe and easy the starting of the wheelchair either up or down stairs or curbs, without diiculty or mechanical shock to the occupant of the wheelchair.

Other important objects and advantageous features of the invention will be apparent from the following descrip-.

tion and the accompanying drawings, wherein, for purposes of illustration only, a specific form of the invention is set forth in detail.

In the drawings:

FIGURE 1 is a right-hand side elevation of a wheelchair of the present invention, showing the traction assemblies retracted upwardly and with the wheels of the wheelchair engaged with the ground and the seat and back untilted;

FIGURE 2 is a bottom plan View of FIGURE 1;

FIGURE 3 is a rear elevation of FIGURE l;

FIGURE 4 is a front elevation thereof;

FIGURE 5 is a left-hand side elevation of the wheelchair, showing the climbing assembly thereat in depressed operative position and a vertical safety rod extended downwardly and engaging the tread of a stair step preliminary to descent of the stair by the wheelchair and the seat and back tilted;

FIGURE 6 is a vertical longitudinal section taken on the line 6-6 of FIGURE 4;

FIGURE 7 is a fragmentary side elevation taken on the line 7-7 of FIGURE 4;

3,133,742 Patented May 19, 1954 FIGURE 8 is a fragmentary side elevation, partly broken away and in section, of one of the horizontal end safety rods and its housing, the safety rod being extended;

FIGURE 9 is a fragmentary vertical transverse section taken on the line 9-9 of FIGURE 5;

FIGURE 10 is a vertical longitudinal section taken on the line 21o- 10 of FIGURE 9 FIGURE 11 is a schematic vertical longitudinal section taken through one of the climbing assemblies, showing one of its shoes depressed and operatively engaged with the corners of stair steps and being moved rearwardly for climbing the stair, while its other shoe is elevated and is being moved forwardly, preliminary to being depressed and moved rearwardly in contact with the stair corners;

FIGURE 12 is a fragmentary vertical transverse section taken on the line 12-12 of FIGURE 5;

FIGURE 13 is a contracted and fragmentary side elevation of the wheelchair and a traction assembly thereof, and showing a vertical safety rod assembly and its manual locking means, the rod being retracted;

FIGURE 14 is a vertical transverse section taken on the line 14-14 of FIGURE 13;

FIGURE 15 is an enlarged fragmentary vertical longitudinal section taken on the line 15-15 of FIGURE 4, showing the vertical safety rod locked in retracted or elevated position;

FIGURE 16 is a view like FIGURE 5, showing the vertical safety rod extended downwardly and supportably engaged with the tread of a stair step or pavement below a sidewalk;

FIGURE 17 is an enlarged vertical transverse sectional detail of the air-bleeding vent of the Vertical safety rod assembly.

Referring in detail to the drawings, wherein like numerals designate like parts throughout the several views, the illustrated wheelchair comprises a crosswise collapsible frame 20, which can be of a substantially conventional collapsible type, involving similar inverted U-shaped sides which provide, at their upper ends horizontal arm rests 22, front perpendicular vertical bars 24 and rear vertical perpendicular bars 26, the rear bars being shorter than the front bars. Horizontal longitudinal brace bars 2S extend between the lower ends of the rear bars 26 at points intermediate the ends of the front bars 24 and are lixed thereto. Lateral wheel brackets 30 extend laterally outwardly from the front vertical bars 24, below the horizontal bars 2S, and carry relatively small diameter front ground-engaging wheels 32. Foot-rest supporting arms 34 extend forwardly and downwardly from upper parts of the front vertical bars 24 and carry a foot-rest 36. A seat 3S is suspended between the frame sides.

A tiltable back rest and seat 41B comprises a pair of rearwardly inclined straight levers 42, having rearwardly extending handles 44, on their upper ends, and a flexible sheet 46 stretched between the levers 42. The levers 42 have substantially horizontal extensions 47 extending forwardly from their lower ends, between which the seat 38 is stretched. The extensions 47 are pivoted, at their forward ends, as indicated at 48, on sleeves 5t) which are slidably circumposed on the front vertical bars 24, above the foot-rest arms 34, whereby the seat and the back rest is adapted to be tilted between untilted and rearwardly tilted positions, by depression and elevation of the climbing mechanism hereinafter described.

The wheelchair' frame 20 further comprises vertical perpendicular auxiliary rear bars 52, spaced behind and parallel to the rear vertical bars 26, which have forwardly extending portions 54, on their upper ends, which are suitably fixed to the rear bars 26, adjacent to their upper ends. As shown in FIGURE 6, the lower ends 56 of the 3 auxiliary vertical bars 52 are on a level with the lower ends 58 of the front vertical bars 24. A horizontal slide 60, located between the rear vertical bars 26 and the auxiliary bars 52, has arcuate seats 62, on its ends, which slidably embrace these bars.

The back rest levers 42 are fulcrumed, at their lower ends, as indicated at 66, on the upper ends of vertical links 68, which are pivoted, at their lower ends, as indicated at 70, on the free ends of the upper arms 72 of bell cranks 73, having lower arms 75, the bell cranks being pivoted as indicated at '77, to the undersides of the frame bars 28, at the lower ends of the rear vertical bars 26.

As shown in FIGURES 3 and 4, the sides of the frame are spaced and connected by transverse rods 74 which cross at their midlength points and are thereat pivoted together, as indicated at 76, the ends of the rear rods '74 being pivoted, as indicated at '77, to the slide 60 and the bar 28, and the front rods 74 to the bar 28, and the sleeve 50, as indicated at 79.

Means is provided to enable the occupant of the wheelchair to partially collapse or spread the frame sides away from each other, without leaving the wheelchair, as for passing through a narrow door. This means comprises a crank handle 80 on the outer end of a screw shaft 82, which extends inwardly from one side of the frame 20 and is journaled through a bearing xed on the corresponding horizontal bar 28, and is threaded through a nut 84 which, as shown in FIGURE 2, is carried by a crossbar 86, extending between the inner ends of a pair of parallel spaced horizontal bars 88, which are xed to the horizontal bar 28 of the other side of the frame 20.

On each of the arm rests 22 a gear casing 90 is mounted, which can comprise a sleeve 92 xedly circumposed thereon, and a hollow pendant portion 94- in which is enclosed a bevel gear wheel 96 which is journaled on a horizontal transverse axis, and has an external crank handle 98, on its laterally outward side. The casing portion 94 has two forwardly and rearwardly spaced and downwardly divergently angled journals 100, through which front and rear worm shafts 102 and 104, respectively extend. These shafts have bevel pinions 106, on their upper ends, which are in mesh with the gear wheel 96. The gear shafts have polygonal lower end portions 108, which slide non-rotatably in related tubular lower shaft sections 110 and 112, respectively, which have worm gears 116, on their lower ends.

Each pair of worm shafts 102, 104 operates components of a traction assembly 118, each of which comprises a horizontal, longitudinally elongated hollow housing 120, longer than the length of the wheelchair sides, which, as shown in FIGURES 6, 9, and 10, comprises a top wall 122, an inclined side wall 124, and an outboard side wall 126. On the lower edge of the inner side wall 124 is an outwardly extending horizontal ange 128, which terminates in an upstanding partition wall 130, of limited height, which has, along its upper edge, a lateral horizontal stop flange 132. The housing top wall 122 is provided, at its middle, with a longitudinal slot 134, and forwardly of the slot the top wall and the side walls are formed with a pair of longitudinally spaced front, upstanding semicircular rotor enclosures 136 and 138; and a pair of similarly longitudinally spaced rear rotor enclosures 140 and 142 are formed on these walls. Fixed to and upstanding from the housing top wall 122, between the front and rear enclosures, are perpendicular vertically elongated front and rear sockets 144 and 146, in which the lower ends of the front vertical bars 24 and the lower ends of the rear auxiliary bars 52 of the frame sides are slidably engaged.

As shown in FIGURES 2, 7 and 8, the outboard side walls 126 of the traction assembly housings 120, at the forward ends thereof, are formed with horizontal longitudinal tubes 148 in whose forward ends horizontal safety rods 150 are slidably engaged, and have enlarged compressible knobs 152, on their outer ends. The tubes 148 have longitudinal slots 154 in the top of their sidewalls, in which rod-extending cables 156 are engaged, which are Secured, at their adjacent ends, as indicated at 158, to the inner ends of the rods. The cables are trained upwardly and rearwardly around pulleys 160 mounted on the tubes 148, at the forward ends of the slots 154, and extend upwardly.

Retracting coil springs 151 are stretched between and connected to the closed ends of the tubes 48 and to the rods 150. The springs 151 extend into counterbores 153, provided in the rods, wherein they are secured, at their ends, as indicated at 155, the other ends of the springs being secured, as indicated at 157. The cables 156 lead upwardly and rearwardly from the pulleys 160, and are adapted to be tied around cable anchors 159, on the outer sides of the arm rests 22 of the chair frame, in stretched condition, for projecting the rods 150, against the resistance of the springs 151.

The safety rods 150 are adapted to be extended and engaged with the pavement or with the tread of a stair step, preliminary to moving the wheelchair to descend the same, and serve to prevent undue forward tilting of the wheelchair before the traction assemblies can assume full supportive contact with the same.

As shown in FIGURES 12 through 16, the outer side walls 126 of the traction assembly housings 120 are provided, between the front and rear pairs of rotor enclosures, with vertical safety rod assemblies 166, which comprise vertically elongated cylinders 168 having closed upper ends 170, and having partition walls 172, adjacent to their open lower ends 174, which are on a level with the bottoms of the housings 120. The partition walls 172 are formed with polygonal central openings 176 through which polygonal vertical safety rods 178 slide, the rods 178 having wheels 180 journaled on their lower ends below the partition walls, in clevises 182 which are wider than the openings 176 and make upward Stop engagement with the partition walls, for positively limiting upward travel of the rods. The sidewalls of the cylinders 168 and the partition walls 172 are formed with horizontal bores 184 in which work stems 186 having enlarged detent heads 188, on their inner ends, which are adapted to engage in selected one of a vertical series of spaced detent notches formed on the adjacent sides of the safety rods 178, for holding these rods in selected downwardly extended positions. Coil springs 192 surround the stems 186 in counterbores 174, in the bores 184 and are compressed between the detent heads 188 and the remote ends of the counterbores 194. Bell cranks cranks 196 are pivoted, as indicated at 198, on the exterior of the cylinders 168, above the stems 186, whose lower arms are articulated to the outer ends of the stems, as indicated at 200, and upper arms connected, as indicated at 202, to the lower ends of detent re'tracting cables 204. The cables 204 lead upwardly and rearwardly to the forward ends of latch arms 206, which are pivoted, as indicated at 208, upon the arm rests 22, at their rear ends. The rear ends of the latch arms 206 are adapted to be engaged beneath spring catches 210, when rearwardly tilted, so that the cables 204 are taut, and the dctent heads 188 withdrawn from the vertical safety rods 178, and these rods are free to fall to extended positions, as indicated in FIGURES 5 and 16, to engage a surface spaced below another surface, whereat the latch arms are released to lock the safety rods 178 in selected extended positions, so that the wheelchair is prevented from tilting forwardly, until the traction assemblies have passed far enough forwardly, beyond the elevated surface, to make substantial operative engagement with the depressed surface when permitted to tilt forwardly thereto, by the retarded and gradual ascent of the safety rods 178.

This retarded and gradual ascent of the safety rods 178 is obtained by means of cushions of air within the cylinders 168 between the closed upper ends 170 thereof, and pistons 212 xed on the upper ends of the rods 178.

The pistons 212 comprise lower, upwardly facing resilient concave discs 214, circumposed on reduced diameter portions 216, on the upper ends of the rods and underlaid by rigid discs 218, rigid upwardly opening rigid cups 220 having bottom walls 222 formed with central openings 224 receiving the reduced portions 216, and nuts 226 threaded on the upper ends of these portions against the bottom walls. The cups 220 have, at their upper ends, lateral lower flanges 228, which bear against the cylinder sidewalls, and which, with narrower upper anges 238, define annular grooves 232, in which upper annular compressible sealing rings 234 are seated, and engage the cylinder sidewalls. Rod-extending coil springs 236 are seated in the cups 220 and are compressed between the cup bottom walls and the closed upper ends 178 of the cylinders and bias the safety rods 178 downwardly, when the detent heads 188 are withdrawn from notches 196 in the rods, in the manner already outlined hereinabove The cylinders 168 have air vents 238, in their sidewalls, adjacent to their upper ends, which, as shown in FIG- URE 17, comprise plugs 240 threaded through horizontal bores 242, formed in the sidewalls. The plugs 240 have conical inner ends 244 which are proportioned to be slightly spaced from the conical inner ends 246 of the bores, into which reduced diameter passages 248 open, which are open to the interior of the cylinders, above the pistons 212. The plugs 240 have relatively small diameter axial passages 251) extending inwardly from their outer ends, which terminate in laterally angled inner end portions 252 which open to the surfaces of the conical inner ends of the passages, into the spaces between these ends, and the conical inner ends of the bores 242. The plugs 240 are adjustable in the bores 242 to limit the venting of air through the vents and thereby determine the resistance to rise of the safety rods in the cylinders 168.

Each of the traction assembly housings 120 contains an inboard traction shoe 254 and an outer traction shoe 256, each of which comprises a horizontal, longitudinally elongated dat resilient bar 258, having upturned ends 260 which bear slidably against the undersides of the housing top walls 122, as shown in FIGURE 6, at points adjacent to the ends of these top walls. Fixed to and extending along the lengths of the undersides of the bars 258 are solid rubber or rubber-like material resilient and compressible traction treads 261, formed with downwardly extending V-shaped traction teeth 263. The bars 258 have upstanding pins 262, located between the ends of the slots 134, which extend upwardly through these slots. The pin 262 of the inboard traction shoe 254 has front and rear coil springs 264 and 266, respectively, secured thereto and stretched to and secured to related adjacent one of the front and rear rotor enclosures. The pin 262 of the outboard traction shoe 256 has front and rear coil springs 268 and 270 secured thereto and stretched to and secured to the same rotor enclosures. This spring arrangement serves to return the traction shoes toward their starting posiions, from forwardly or rearwardly extended positions.

rEhe bars 258 of the traction shoes are engageable by undersides of rotors journaled on horizontal transverse axes in the front rotor enclosures 136, 138 and the re-ar rotor enclosures 148 and 142, as shown in FIGURES 6 and 9. As shown in FIGURE l0, the adjacent front and rear rotor enclosures 138 and 140 have projections 272, on their peripheral walls through which the worm gears 116 of the Worm shafts 182, 104 are journaled. The worms are in mesh with worm wheels 274, which are parts of the related rotors. The worm wheels 274 are fixed on shafts 276 which are journaled on the side walls of the housings 128, within the related enclosures, and which carry similar but diametrically opposed cam wheels 278 and 288, respectively, which bear upon the bars 258 of the inboard and outboard traction shoes.

The inboard cam wheels 278 comprise semi-circular or sector gears 282, which, as shown in FIGURE 6, engage racks 284 formed on the inboard traction shoe bars 258, behind the pins thereof, for producing rearward movements of these shoes, or racks 286, formed on the undersides of the top walls 122 of the housings, at the forward ends of the slots 134, for producing forward or rocking movements of the inboard traction shoes, against the resistance of the return springs 264, 266, 268 and 270, according to the positions of the inboard shoes, when the crank handles 98 on the wheelchair frame sides are rotated by the occupant, in selected directions.

Remote front and rear rotorsl in the remote front and rear enclosures 136 and 142, comprise similar inboard and outboard segmental cam wheels 288 and 290, which are diametrically opposed to each other and have smooth eripheral surfaces which bear, at different times, upon the bars 258 of the traction shoes.

Extending at upward angles, at the front and rear ends of the housings 128, on the outboard sides thereof are brackets 292 and 294, respectively, through which are journaled the shafts 296 of leading and trailing starting wheels 298 and 389, respectively, which are of relatively large diameter, and have compressible toothed traction bands 382 around their peripheries. The wheels 298 and 388 are located at the outboard sides of the housings 128, and their lower edges are substantially on a level with the traction bodies of the traction shoes. The shafts 296 have sprocket wheels 384, on their inboard ends, over which front and rear sprocket chains 306 and 388, respectively, are trained, which are also trained around sprocket wheels 318 on the inboard ends of the shafts of the intermediate rotors, whereby the starting wheels are rotated in directions to climb or to descend a stair, in coordination with the endwise movements of the traction shoes.

The traction assemblies are raised and lowered, relative to the sides of the frame 28, and locked in their lowered positions, by means of lever systems, each of which comprises a manual vertical main lever 312 which is provided, intermedi-ate its ends, as indicated at 314 on a related horizontal frame side bar 28, and has, on its upper end, a forwardly displaced handle 316. A forward horizontal link 318 is pivoted, at its rear end, to the lower end of the lever 312, as indicated at 320, extends forwardly therefrom. The link 318 is pivoted, Iat its forward end to the adjacent ends of front upper and lower toggle levers 322 and 324, respectively, the respective upper and lower ends of which are pivoted, as indicated at 326 and 328, respectively, to the front vertical bars 24 of the wheelchair frame sides, above the horizontal bar 28, and to the front traction assembly socket 144. An upper or rear horizontal link 330 is pivoted, at its forward end, as indicated at 332, to the main lever 312, at a point spaced above the fulcrum thereof, and is pivoted, at its rear end, as indicated at 334, to the adjacent ends of rear, vertical upper and lower toggle levers 336 and 338, respectively, whose respective upper and lower ends are pivoted, as indicated at 340 and 342, respectively to the rear vertical auxiliary bar 52 of the frame sides, at points spaced above the bars 28 and to the rear sockets 146 of the traction assemblies. The arrangement is such that when the main lever 312 is swung rearwardly and upwardly from the forwardly inclined position of FIGURE 6 to the upright position of FIG- URE 5, the traction assemblies 118 are pushed downwardly relative to the wheelchair frame Sides, so that the wheelchair wheels including the front wheels 32 and bicycle-size rear wheels 33 journaled on the auxiliary vertical bars 52, are elevated out of contact with the ground, and the traction assembly traction shoes can engage with the ground and bear the Weight of the wheelchair.

F or producing rearward tilting of the back rest and seat assembly 40, as the main lever 312 is moved to depress the traction assemblies, and for producing forward tilting of the back rest and seat assembly, as the traction assemblies are retracted, a cable 34d is provided, which, as shown in FIGURES l and 5, is anchored, as indicated at 346, at its rear end to the main lever 312, at a point adjacent to and below the pivot 332, is trained around and under a pulley 348, extends forwardly therefrom, and is anchored, as indicated at 350 on a front 144.

The pulley 348, as shown in FIGURES 1, 5, and 6, is pivoted on the lower arm 75 of the bell crank 73. With this arrangement, rearward swinging of the main lever 312, from the forwardly angled position, shown in FIG- URES 1 and 6, to its erect position, shown in FIGURE 5, permits the bell crank 73 to be tilted downwardly, from an elevated position, by the weight of the occupant of the back rest and seat assembly 40, accompanied by rearward tilting of this assembly. When the main lever 312 is pushed forwardly and downwardly, the cable 344- is tensioned, and, in effect shortened, so that the bell crank 73 and the assembly 40 are tilted upwardly, so that the assembly 4i) is returned to its normal position, wherein the seat 38 is substantially horizontal.

In operation, when a stair or curb is to be climbed or descended, the wheelchair is wheeled to the stair or curb, in the corresponding direction, and one or both of the horizontal safety rods 150 are extended. The vertical safety rods 178 are then released so that they are spring-pressed downwardly and can engage the tread of a step, in the case of descending a stair, below the level of the floor, and when so engaged be locked in extended chair supporting position to prevent precipitation from tilting of the chair. The wheelchair is started forwardly over the brink of the stair, with the traction shoes depressed and the chair wheels raised from the ground, and with the back rest and seat assembly 4t) tilted rearwardly and the alternate forward reach and retraction of the traction shoes put into effect by turning the hand cranks 9S, so that the traction shoes pull the chair over the edges of the first and the succeeding steps of the stair and at the same time prevent the weight of the chair from producing forward sliding of the chair down the stairs. The related starting wheels engage the stairs in advance of the traction shoes, so as to bring the traction shoes to the proper level for smoothly engaging the edges of the steps and prevent digging7 of the forward ends of the traction assembly housings 12d and the forward ends of the traction shoes into the risers of the stair steps. Such descents or climbs of stairs or curbs can be made in either direction, and the horizontal safety rods extended to serve to bear against the bottom level or floor at the lower end of a stairs and tilt the chair back toward the horizontal as this level is reached, prior to the engagement of the related starting wheels therewith. The horizontal safety rods also serve to engage a wheel or other obstruction on the bottom level in advance of and prevent undesirable contact of the traction assembly housings and the starting wheels with such obstruction. The actions of the inboard and outboard traction shoes 254 and 256, respectively, include, in the case of forward movement of the wheelchair on a surface, forward reach of one of the shoes while elevated out of contact with the surface, followed by downward flexure of this shoe into contact with the surface, accompanied by rearward traction movement; and at the same time the other traction shoe moves forwardly, out of contact with the surface, in a retracting movement, until it reaches its fully retracted position, whereat this other shoe is flexed down into contact with the surface as it moves rearwardly in a traction movement.

When the main lever 312 is operated forwardly to its extreme rearward or erect position, in depressing the traction shoe assemblies into contact with the ground, the front and rear toggle levers 332, 334 and 336 and 338 are respectively pushed forwardly and rearwardly to overcenter locking positions, as shown in FIGURE 5, so that these assemblies are securely and safely locked in these positions, unless and until the main lever 312 is swung forwardly out of erect locking position. The wheelchair can be steered and controlled by the occupant, by rotating the crank handles 98 in different directions, and by operating them in the same direction at different speeds.

It is to be observed that the crank handle operated drive means for the worm shafts 102 and 1.04 could be readily replaced by electric motor driven means, having appropriate control means.

Although there has been shown and described a preferred form of the invention, it is to be understood that the invention is not necessarily confined thereto, and that any change or changes in the structure of and in the relative arrangements of components thereof are contemplated as being within the scope of the invention as defined by the claims appended hereto.

What is claimed is:

1. A wheelchair comprising a seat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, each of said traction assemblies comprising a horizontal housing, inboard and outboard traction shoes supported within the housing and adapted to project at different times from the housing into contact with the ground, and driving means mounted on the frame and connected to the shoes for producing alternate elevation and depression of the shoes accompanied by movements of the shoes in opposite directions, and driving means on a frame side and operatively connected to the shoes, said traction shoes being slidably engaged with their housing for endwise movements relative thereto, said traction shoes comprising resilient bars having upturned end portions bearing against the housing, and resilient and compressible notched treads fixed to the underside of the bars, said driving means comprising longitudinally spaced pairs of inboard and outboard rotors mounted on the housing, said rotors comprising semi-circular cam wheels, the cam Wheels of each rotor being diametrically opposed to each other and engageable at different times with the shoe bars for depressing the same, some of said cam wheels being sector gears, said shoe bars and said housing having racks with which the rotor gears are operatively engageable at different times for imparting endwise movements of the traction shoes in opposite directions, and manually operated gear means connected to the sector gears.

2. A wheelchair comprising a seat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame Wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, each of said traction assemblies comprising a horizontal housing, inboard and outboard traction shoes supported within the housing and adapted to project at different times from the housing into contact with the ground, and driving means mounted on the frame and connected to the shoes for producing alternate elevation and depression of the shoes accompanied by movements of the shoes in opposite directions, and driving means on a frame side and operatively connected to the shoes, said traction shoes being slidably engaged with their housing for endwise movements relative thereto, said traction shoes comprising resilient bars having upturned end portions bearing against the housing, and resilient and compressible notched treads fixed to the underside of the bars, said driving means comprising longitudinally spaced pairs of inboard and outboard rotors mounted on the housing, said rotors comprising semicircular cam wheels, the cam wheels of each rotor being diametrically opposed to each other and engageable at different times with the shoe bars for depressing the same, some of said cam wheels being sector gears, said shoe bars and said housing having racks with which the sector gears are operatively engageable at different times for imparting endwise movements of the traction shoes in opposite directions, and manually operated gear means connected to the sector gears, and spring means acting between the traction shoes and the housing and resisting endwise movements of the shoes in opposite directions.

3. A wheelchair according to claim 2, wherein said housing has starting wheels at its ends whose undersides are substantially on a level with the undersides of the shoes and having toothed peripheries, and means drivingly connecting the starting wheels to the rotors having sector gears.

4. A wheelchair according to claim 3, wherein said housing has horizontal safety rods slidably mounted thereon for extensile movement, and means on the frame and operatively connected to said rods for extending the horizontal safety rods.

5. A wheelchair comprising a seat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, each of said traction assemblies comprising a horizontal housing, inboard and outboard traction shoes supported Within the housing and adapted to project at different times from the housing into contact with the ground, and driving means mounted on the frame and connected to the shoes for producing alternate elevation and depression of the shoes accompanied by movements of the shoes in opposite directions, and driving means on a frame side and operatively connected to the shoes, said operating means comprising a vertical main lever pivoted intermediate its ends on a frame side, pairs of toggle levers pivoted to the frame side at points spaced longitudinally therealong and at vertically spaced points, each pair of toggle levers being pivoted to each other, and links pivoted at one end to the main lever and at their other ends to the pivotal connections of the toggle levers, said main lever being swingable in one direction to move the pairs of toggle levers into over-center locking positions wherein the traction assemblies are depressed for engagement of the ground and the frame wheels are elevated out of coutact with the ground, said main lever being swingable in the opposite direciton for elevating the traction assemblies out of contact with the ground and engaging the frame wheels supportively with the ground.

6. A wheelchair comprising a seat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, each of said traction assemblies comprising a horizontal housing, inboard and outboard traction shoes supported within the housing and adapted to project at different times from the housing into contact with the ground, and driving means mounted on the frame and connected to the shoes for producing alternate elevation and depression of the shoes accompanied by movements of the shoes in opposite directions, and driving means on a frame side and operatively connected to the shoes, said traction shoes being slidably engaged with their housing for endwise movements relative thereto, said housing having intermediate its ends a vertical safety rod mounted to be moved from an upwardly retracted inoperative position to a depressed operative position wherein the Vertical safety rod extends below the traction shoes for supportive engagement with the ground, and means for projecting the vertical safety rod to depressed position.

7. A wheelchair according to claim 6, which includes in addition a vertical air cylinder fixed on the housing, said cylinder having a closed upper end and a partition wall at its lower end, said partition wall having an opening through which the vertical safety rod works, said safety rod having a piston working in the cylinder above the partition wall, said cylinder having a restricted air vent at its upper end.

8. A wheelchair according to claim 7, wherein said depressing means comprises a depressing spring compressed between the closed upper end of the cylinder and the piston.

9. A wheelchair according to claim 8, which includes in addition spring-pressed detent means on the sidewall of the cylinder having a head, said safety rod having vertically spaced notches adapted to be selectively engaged by the head, and manual releasing means for the detent means.

l0. A wheelchair according to claim 9, wherein said manual releasing means for the detent means comprises a bell crank pivoted on the cylinder and having a first arm connected to the detent means and a second arm, and lockable latch means on the frame and operatively connected to said other arm.

11. A wheelchair in accordance with claim 2, wherein said housing has an open bottom, an inboard side wall, an outboard side wall and a top wall, said top wall and said side walls being formed to provide semicircular enclosures for the rotors, some of said rotors having Worm wheels connected to related cam wheels and said enclosures having peripheral walls, said driving means comprising worms journaled on said peripheral walls and in mesh with the worm Wheels, said worms having upwardly eX- tending worm shafts having bevel pinions on their upper ends, and a bevel gear wheel journaled on the frame, with which the pinions are in mesh, and means for rotating the gear wheel.

l2. A wheelchair comprising a scat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the trarne and connected with the traction assemblies, each of said traction assemblies comprising a horizontal longitudinal open bottom housing having a top wall, inboard and outboard traction shoes arranged side-by-side within the housing, said shoes comprising resilient bars having upturned ends slidably engaged with the underside of the housing top wall with the portions of the bars between their ends spaced downwardly from the top wall, means slidably guiding the bars on the housing for endwise movements relative thereto in opposite directions, said shoe bars having compressible traction treads Xed on their undersides, and driving means for the shoes mounted on the frame and the housing and individually engageable with the traction shoes and adapted to produce endwise movements of the shoes in opposite directions accompanied by alternate downward tlexing of the shoes into operative positions in contact with the ground, one shoe being in operative position and moving in a direction to move the wheelchair and the other shoe being in a retracted position out of contact with the ground and moving in the opposite direction.

13. A wheelchair comprising a seat frame having sides, said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, each of said traction assemblies comprising a horizontal longitudinal open bottom housing having a top wall, inboard and outboard traction shoes arranged side-by-side within the housing, said shoes comprising resilient bars having upturned ends slidably engaged with the underside of the housing top wall with the portions of the bars between their ends spaced downwardly from the top wall, means slidably guiding the bars on the housing for endwise movements relative thereto in opposite directions, said shoe bars having compressible traction treads xed on their undersides, and driving means for the shoes mounted on the frame and the housing and individually engageable with the traction shoes and adapted to produce endwise movements of the shoes in opposite directions accompanied by alternate downward flexing of the shoes into operative positions in contact with the ground, one shoe being in operative position and moving in a direction to move the wheelchair and the other shoe being in a retracted position out of contact with the ground and moving in the opposite direction, said traction shoes extending substantially the full length of the housing. l

14. A wheelchair comprising a seat frame having sides,

said sides having ground-engaging wheels, traction assemblies slidably engaged with the frame sides and adapted to be moved downwardly from elevated positions whereby the traction assemblies are out of contact with the ground and the frame is supported on its wheels to a depressed position wherein the frame Wheels are out of contact with the ground and the traction assemblies support the frame on the ground, operating means on the frame and connected with the traction assemblies, a back rest and seat assembly supported between the seat frame sides to tilt forwardly and rearwardly relative to the trame, and means operatively connecting said assembly to at least one of the traction assemblies whereby the said assembly is maintained in a forwardly tilted position while the traction assemblies are elevated and said assembly is tilted rearwardly as the traction assemblies are depressed.

References Cited in the le of this patent UNITED STATES PATENTS 756,767 Younglren Apr. 5, 1904 1,617,261 Maksabedian Feb. 8, 1927 2,818,910 Hawkins Jan. 7, 1958 2,824,597 Lerman Feb. 25, 1958 3,068,950 Davidson Dec. 18, 1962 3,111,331 Locke Nov. 19, 1963 FOREIGN PATENTS 9,240 Great Britain Dec. 9, 1915 693,983 Great Britain July 8, 1953 325,764 Germany Sept. 17, 1920 808,411 Germany July 16, 1951 OTHER REFERENCES Pamphlet: Wanted: A Stair-Climbing Wheel Chair, by National Inventors Council, January 1962, pages 16-26 relating to the Freeman Wheelchair. 

1. A WHEELCHAIR COMPRISING A SEAT FRAME HAVING SIDES, SAID SIDES HAVING GROUND-ENGAGING WHEELS, TRACTION ASSEMBLIES SLIDABLY ENGAGED WITH THE FRAME SIDES AND ADAPTED TO BE MOVED DOWNWARDLY FROM ELEVATED POSITIONS WHEREBY THE TRACTION ASSEMBLIES ARE OUT OF CONTACT WITH THE GROUND AND THE FRAME IS SUPPORTED ON ITS WHEELS TO A DEPRESSED POSITION WHEREIN THE FRAME WHEELS ARE OUT OF CONTACT WITH THE GROUND AND THE TRACTION ASSEMBLIES SUPPORT THE FRAME ON THE GROUND, OPERATING MEANS ON THE FRAME AND CONNECTED WITH THE TRACTION ASSEMBLIES, EACH OF SAID TRACTION ASSEMBLIES COMPRISING A HORIZONTAL HOUSING, INBOARD AND OUTBOARD TRACTION SHOES SUPPORTED WITHIN THE HOUSING AND ADAPTED TO PROJECT AT DIFFERENT TIMES FROM THE HOUSING INTO CONTACT WITH THE GROUND, AND DRIVING MEANS MOUNTED ON THE FRAME AND CONNECTED TO THE SHOES FOR PRODUCING ALTERNATE ELEVATION AND DEPRESSION OF THE SHOES ACCOMPANIED BY MOVEMENTS OF THE SHOES IN OPPOSITE DIRECTIONS, AND DRIVING MEANS ON A FRAME SIDE AND OPERATIVELY CONNECTED TO THE SHOES, SAID TRACTION SHOES BEING SLIDABLY ENGAGED WITH THEIR HOUSING FOR ENDWISE MOVEMENTS RELATIVE THERETO, SAID TRACTION SHOES COMPRISING RESILIENT BARS HAVING UPTURNED END PORTIONS BEARING AGAINST THE HOUSING, AND RESILIENT AND COMPRESSIBLE NOTCHED TREADS FIXED TO THE UNDERSIDE OF THE BARS, SAID DRIVING MEANS COMPRISING LONGITUDINALLY SPACED PAIRS OF INBOARD AND OUTBOARD ROTORS MOUNTED ON THE HOUSING, SAID ROTORS COMPRISING SEMI-CIRCULAR CAM WHEELS, THE CAM WHEELS OF EACH ROTOR BEING DIAMETRICALLY OPPOSED TO EACH OTHER AND ENGAGEABLE AT DIFFERENT TIMES WITH THE SHOE BARS FOR DEPRESSING THE SAME, SOME OF SAID CAM WHEELS BEING SECTOR GEARS, SAID SHOE BARS AND SAID HOUSING HAVING RACKS WITH WHICH THE ROTOR GEARS ARE OPERATIVELY ENGAGEABLE AT DIFFERENT TIMES FOR IMPARTING ENDWISE MOVEMENTS OF THE TRACTION SHOES IN OPPOSITE DIRECTIONS, AND MANUALLY OPERATED GEAR MEANS CONNECTED TO THE SECTOR GEARS. 